Shutter assembly for photographic equipment

ABSTRACT

A between-the-lens shutter which includes a sealed casing containing a liquid of selected index of refraction to couple two optical elements of the camera lens and which also houses a pair of shutter blades. The shutter blades are mounted to pivot about an axis offset with respect to an aperture through the casing and are controlled by a common cocking-releasing cam. The shutters are cocked sequentially and released simultaneously. A high shutter speed effect is achieved by allowing both shutter blades, when released to return simultaneously toward their normal or rest positions and a slow shutter speed effect is achieved by delaying the return of the second-cocked shutter blade when the two blades are released simultaneously. The delayed return is achieved by a latch made operative by slightly shifting the pivot mounting for the two shutter blades, the latch temporarily holding the second shutter blade in cocked position and being disengaged from this shutter blade in response to movement of the other shutter blade to its rest position after both blades have been simultaneously released by the cam.

112*L7 73 XR 39718-9079 United States Patent [1 1 3,718,079 Fuller 1Feb. 27, 1973 [5 1 SHUTTER ASSEMBLY FOR 57 ABSTRACT PHOTOGRAPHICEQUIPMENT A between-the-lens shutter which includes a sealed [75]Inventor: David L. Fuller, Atlanta, Ga. casing containing a liquid ofselected index of refrac- [73] Assigneez Script), Inc. Atlanta Ga tionto couple two optical elements of the camera lens [22] Filed: Oct. 8,1971 shutter blades are mounted to pivot about an axis off- [211 App] No187 772 set with respect to an aperture through the casing and arecontrolled by a common cocking-releasing cam.

The shutters are cocked sequentially and released [52] US. Cl ..95/62,350/267 simultaneously A high shutter speed effect is achieved [51] Int.Cl. ..G03b 9/14 by allowing both shutter blades, when released to Fieldof Search return simultaneously toward their normal or rest 272positions and a slow shutter speed effect is achieved by delaying thereturn of the second-cocked shutter References Cited blade when the twoblades are released simultaneously. The delayed return is achieved by alatch made UNITED STATES PATENTS operative by slightly shifting thepivot mounting for 3,295,913 1/1967 Walther ..350/179 X the two shutterblades, the latch temporarily holding 2,300,344 7/1957 Durst e 5/ thesecond shutter blade in cocked position and being 2,827,339 3/1958disengaged from this shutter blade in response to 2,917,982 12/ l959Martin ..95/62 movement of the other shmter blade to its rest posi tionafter both blades have been simultaneously Primary Examiner-Joseph F.Peters, Jr. released by the cam Attorney-Edward Taylor Newton et al.

14 Claims, 18 Drawing Figures OPTICA L and which also houses a pair ofshutter blades. The

PATENTED FEB 2 7 i373 SHEET 10F 3 04m 1. fuzz/5b PA nrmzmn SHEET 3 OF 3IIIIIIIIJ n SHUTTER ASSEMBLY FOR PI-IOTOGRAPI-IIC EQUIPMENT BACKGROUNDOF THE INVENTION The art relating to camera shutters in general has beenvery highly developed and an almost infinite variety of mechanisms andtechniques have been employed. Many of them relate to specific means bywhich variable shutter speed is attained. Shutters for use between lenselements of an optical system have also been developed and are usuallyreferred to as betweenthe-lens shutters.

However, a between-the-lens shutter housed within a casing which issealed and contains a body of opticalcoupling liquid has not, to myknowledge, been developed in the prior art. Further, I do not know ofsuch an arrangement wherein selection of one of two shutter speedeffects is provided.

BRIEF SUMMARY OF THE INVENTION The present invention is directed to anextremely simple shutter blade arrangement whereby a betweenthe-lensshutter may be housed within a sealed casing containing an opticalcoupling liquid. The arrangement consists simply of two spring-returnedshutter blades mounted on a common pivot and associated with acocking-releasing cam which cocks the blades sequentially and releasesthem simultaneously. Each blade has an aperture or window whichregisters, in an intermediate position of each blade, with a casingaperture system which allows the image-producing light to reach thephotosensitive film associated with the optical system of the camera.The return movements of the shutter blades are so adjusted as to causethese windows to register simultaneously with the casing aperture systemafter the blades are released by the cam and before the blades reachtheir rest positions. Neither of these windows registers with anyportion of the easing aperture system when in either the rest positionor the cocked position, so that the sequential cocking of the bladespositively excludes the passage of light to the photosensitive filmduring cocking. When the two shutter blades return simultaneously fromtheir cocked to their rest positions, a high shutter speed effect isattained.

A slow shutter speed effect, one-half of that achieved as above, isobtained by allowing only one of the shutter blades to return to itsrest position during exposure of the photosensitive film. This action isobtained by providing a further window in the other shutter blade whichregisters with the casing aperture system when such other blade is inits cocked position, and by retaining this other blade in its cockedposition after the blades are released by the cam until the stated oneblade reaches or approaches its rest position.

The blade which is held or retained in cocked position after its releaseby the cam to achieve the slow shutter speed effect, is so retainedthrough the use of a latch which normally does not engage this blade butwhich may do so when the pivot mounting for the blades is shiftedslightly under selective control of the operator.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. 1 is an elevational viewshowing the shutter casing with shutter blades in normal position;

FIG. 1A is a view of the cam mechanism corresponding to the FIG. 1position;

FIG. 2 is a sectional view illustrating the casing in as sociation withcomponents of the optical system and also illustrating the cam drive andshutter speed adjusting mechanism;

FIG. 3 is a view similar to FIG. 1 but showing the first blade beingcocked;

FIG. 3A is a view of the cam corresponding to FIG. 3.

the first blade fully cocked;

FIG. 4A is a view of the cam corresponding to FIG.

FIG. 5 is a view similar to FIG. 4 but showing the second blade beingcocked;

FIG. 5A is a view of the cam corresponding to FIG.

FIG. 6 is a view similar to FIG. 4 but showing the second blade fullycocked;

FIG. 6A is a view of the cam corresponding to FIG.

FIG. 7 is a view similar to FIG. 6 but showing the blade after theirrelease from the cam;

FIG. 7A is a view of the cam corresponding to FIG.

FIG. 8 is a view similar to FIG. 1 but showing the blades shifted fromslow shutter speed effect;

FIG. 9 is a view showing the first blade moving into cocked position;

FIG. 10 is a view showing the first blade cocked and the second blademoving into cocked position;

FIG. 11 is a view showing both blades cocked and the second bladelatched;

FIG. 12 is a view showing the first blade after release and return tonormal position in which the second blade is released for return to itsnormal position.

DETAILED DESCRIPTION OF THE INVENTION With reference first of all moreparticularly to FIG. 2, the shutter assembly of this invention will beseen to consist of a casing including a cup-shaped main body portionindicated generally by the reference character 10 and a cover plate 12,the main body portion and the cover plate being affixed together bysuitable fasteners or the like so that the casing defines a cavity orchamber 14 filled with optical coupling fluid of index of refractioncompatible with the optical system with which the shutter assembly isassociated. The cupshaped main body portion and cover plate of thecasing are hermetically sealed to retain the optical coupling liquidwithin the cavity 14 and the housing also contains a pair of shutterblades 16 and 18 lying in overlapped relation as is shown, the shutterblade 16 having a hub portion 20 pivotally mounted on a journal 22 andthe external surface of which forms a journal for the shutter blade 18as indicated by the reference character 24. The journal 22 is fixed to astub shaft 26 and the two elements 22 and 26 are mounted in eccentricrelationship so that, in response to rotation of the FIG. 4 is a viewsimilar to FIGS. 1 and 3, but showing stub shaft 26 to an angle of 180,the effective pivot axis of the two blades 16 and 18 may be shiftedbetween the position shown for the axis 28 and the position shown forthe axis 30, the purpose of which will be presently apparent. The stubshaft 26 projects outwardly through the casing and is journalled thereinas indicated by the reference character 32, it being understood thatsuitable seal means is associated between the casing and the stub shaft26 to retain the hermetic seal as aforesaid.

The assembly also includes a further stub shaft 34 projecting throughthe casing in the bearing portion 36 thereof which is provided with aseal, not shown, similarly to the relationship of the casing to the stubshaft 26, and the stub shaft 34 has a primary cam arm assembly 38 fixedthereto for rotation therewith and, additionally, there is provided asecondary cam arm assembly 40 having limited lost motion with respect tothe primary cam arm 38 and the stub shaft 34 but otherwise rotatabletherewith, all as will hereinafter be apparent.

The two opposed wall portions 42 and 44 of the easing assembly areprovided with aligned openings 46 and 48 which define an aperturethrough which light may pass, under control of the shutter blades 16 and18 as hereinafter described for permitting the imageproducing effect onthe photosensitive film associated with the optical system of thecamera. The optical system may be of the type such as disclosed, forexample, in my copending application Ser. No. 94,830 filed Dec. 3, 1970and, as is shown in FIG. 2, the shutter assembly is interposed betweentwo optical elements 50 and 52 thereof. For this purpose, the outersurfaces 54 and 56 of the wall portions 42 and 44 are spaced apartthrough a selected distance and are of flat form, obtained by suitablemilling or other machining operation to provide mounting surfacesagainst which the optical elements 50 and 52 respectively are engagedand secured. The optical elements thus close the openings 46 and 48 andretain the hermetic seal for the casing and shutter assembly so as toretain the optical coupling liquid within the cavity 14. It will beappreciated that such a system forms what is commonly referred to as abetween-the-lens shutter system.

With reference more particularly to FIG. 1, the details of the shutterassembly will be more readily apparent. As shown, the inner surface 58of the wall 42 is provided with pins 60 and 62 which pivotally receivethe respective bracket members 64 and 66 which serve as anchors for oneend of the respective spring biasing elements 68 and 70. Each of thebrackets 64 and 66 is provided with a slot such as that indicated by thereference character 72 and a screw element; 74 projects through the slotand is threadedly engaged with the wall 42 to allow the brackets 64 and66 to be moved thereby to adjust the bias of each spring 68 and 70 to aselected value.

The spring 68 is connected at its opposite end to the shutter blade 16whereas the spring 70 is connected to the shutter blade 18 and thepretension on the spring elements serves normally to retain the twoshutter blades in their rest or normal positions as is shown in FIG. 1,engaging against the stop elements 76 and 78 respectively. On the otherside of the pivot axis for the shutter blades, the arm portions 80 and82 thereof carry cam follower elements 83 and 85 for engagement with therespective elements of the cam assembly. The operation of the camassembly is such as to cock first the blade 16 from its rest positionshown in FIG. 1 to a cocked position as is shown in FIG. 4 and then tomove the shutter blade 18 from its rest position shown in FIG. 1 to acocked position as is shown in FIG. 6 and, thereafter, the bladessimultaneously are released by the cam so as to permit the biasing means68 and to return the blades to their normal or rest positions. In theprocess of returning to their rest positions from their cockedpositions, openings in the blades sweep past the openings 46 and 48 inthe casing and simultaneously register therewith and with each other toeffect exposure of the photosensitive film associated with the cameraassembly. When both shutter blades 16 and 18 are permitted to returnfrom their cocked to their normal positions simultaneously, as is shownin FIG. 7, after sequential cocking by the cam means, a high shutterspeed effect is obtained inasmuch as the two blades are moving inrelatively opposite directions, whereas in another position of thedevice, the blade 18 which is cocked after the blade 16 has been cockedremains in its cocked position until the blade 16 returns to its restposition so that the shutter speed effect is one half the speed of theaforementioned shutter speed effect attained by simultaneous movement ofboth blades from their cocked to the rest positions, all as willhereinafter be described.

For the purpose of obtaining the high shutter speed effect, the shutterblade 16 is provided with an opening or window 84 and the shutter blade18 is provided with an opening or window 86. Each of these openings isnon-aligned with the aperture openings 46, 48 when the blades are intheir rest positions and when the.

blades are also in their cocked positions, as will be evident from astudy of FIGS. 1 and 6 respectively. However, when the blade 18 is inits cocked position, it also presents an opening 88 which is in registerwith the aperture defining openings 46, 48 in the casing assembly. Thepurpose of this arrangement is to allow for the slow speed shuttereffect hereinafter described.

For the sequence of operations illustrated in FIGS. 1 and 3-7 inclusive,it will be understood that the high speed shutter effect is attained andthat this effect is attained by virtue of the fact that the stub shaft26 is rotated to such a position as effects the location of the pivotaxis for the blades 16 and 18 along the axis 28 (FIG. 2) at which timethe two shutter blades 16 and 18 are shifted relatively radiallyinwardly with respect to the side wall surface 90 of the casing so thatneither is engageable with the latching mechanism hereinafter described.Starting from the sequence illustrated in FIG. 1A, the cam assembly isrotated in the direction of the arrow 92 until the ramp portion 94 ofthe primary cam finger 96 engages the cam follower 83 and causes theblade 16 to begin its movement from its rest position toward its cockedposition, FIGS. 3 and 3A. Further rotation of the cam assembly in thedirection of the arrow 92 causes the follower 83 to engage on theelongated toe portion 98 of the aforesaid cam finger 96, at which timethe blade 16 has reached its fully cocked position whereat its opening84 has swept past the aligned apertures 46, 48 and now resides in aposition on the opposite side thereof, as is shown in FIG. 4.

Continued motion of the cam assembly in the direction of the arrow 92causes the follower bf (FlG. 5A) to approach the end of the elongate toeportion 9% of the cam finger 96 and, at the same time, causes the camfollower $5 to engage the ramp portion ilhtl) of the secondary camfinger M92. As was previously discussed, the secondary cam has lostmotion with respect to the shaft 34 and the primary cam assembly 38, byvirtue of the fact that the stub shaft 34 carries a transverse pin i104engaging within elongated slot portions res and 108 of the hub portionof the secondary cam assembly 40. As soon as the follower 85 is engagedby the ramp ft, the lost motion is assured of being taken up such thatthe preceding secondary cam finger iilh positions itself such that itselongate toe portion 1112 effects a continuation of the elongate toe 98of the cam finger 96 of the primary cam assembly, see particularly lFlG.SA. At this time, the first cocked shutter blade 16 will remain in itscocked position as is shown in FlG. 5 whereas the second shutter bladelid will be moved from its rest position toward its cocked position.Continued motion of the cam assembly in the direction of the arrow 92will cause the cam follower 8 to ride upon the elongate toe portionilild of the secondary cam finger W2 whereas the cam follower b3 willcorrespondingly be engaged on the toe portion 112 of the secondary camfinger 1110, as is shown in FIG. 6A, at which point both shutter blades16 and i8 will be in their fully cocked position as is illustrated inFIG. 6.

As the cam assembly is rotated further beyond the position shown in FIG.6A and as is illustrated in FIG. 7A, the two cam followers 83 and d5simultaneously will be released from control by the cam assembly and thetwo biasing means 68 and 70 thereby simultaneously move the blades M and118 in relatively opposite directions as is indicated by the arrows H116and i118 simultaneously to return from their cocked to their restpositions. in the position illustrated in FllG. 7, the two blades 16 andlit are just at that position in which the two openings dd and 86thereof are in registry with each other and with the openings 36, 4tallowing for full light transmission through the aperture system. Thetwo shutter blades are moved in relatively opposite directions atsubstantially the same velocities and the shutter speed effect will thusbe twice that attained by the speed of either blade alone.

FIG. 7A also shows the fact that the secondary cam assembly is kickedahead when release of the cam followers 83 and 85 takes place and byvirtue of continued rotation of the cam assembly in the direction of thearrow, 92, the kicking ahead of the secondary cam being indicated by theintermediate position of the secondary cam in FIG. 7A and by virtue ofits kicked movement as indicated by the arrow 112413. By providing thislost motion between the primary and secondary cam members, a very smalland compact cam assembly is permitted and, as well, the dimensionalcharacteristics of the blade arms or legs MD and $2 and the dispositionof the followers 83 and $5 is permitted. in addition, such anarrangement prevents an undesirable reflection of torque back thru stubshaft 341 at the time shutter blades 16 and it} are released; thusassuring a smooth operating cycle.

By rotating the stub shaft 266 180 so that the effective pivot actionsof the shutter blades 16 and w reside along the axis 3th, rather thanalong the axis 28, a slow shutter speed effect may be obtained as isillustrated in FIGS. 8-12. As is shown in FIG. 8, the inner wall of thecasing assembly it is cut away as indicated at reference character i122and i243 and a latch member 126 is mounted about a pivot axis 12%, thelatch mechanism being spring biased so that its latch head 111th, FIG.11ft, normally engages a stop member 132 secured to the wall 5% and withthe lateral portion of the head HEW projecting sufficiently far as to beengaged by both the blade rs and the blade 18 in the fashion hereinafterdescribed.

in H6. 8, it will be seen that in the normal positions of the two bladesrs and lid, the blade 16 engages the latch 126 and earns it away fromits stop 132, so that the head 1136i rests uponand engages the outeredge of the blade 16 as shown. When the pivot axis is at the position293, the blades clear the head 13b of the latch but when the pivot axishas been shifted to the axis 30 as is shown in FIGS. h-iZ, the bladesmay engage with the latch. FliG. 9 shows the blade in in the process ofbeing moved from its rest to its cocked positions and after havingcleared the head 13d of the latch E26, permitting the latter to springto engagement with its stop 332. When the blade it? is in its fullycocked position as is shown in FIG. W and the other blade 18 is beingsequentially cocked toward its cocked position as is shown in H6. iltl,the outer edge of the blade 18 ultimately will engage the head 1% of thelatch mechanism and, when the blade 1% is in its fully cooked positionas is shown in FIG. ill, the head 13th of the latch mechanism 126engages in the notch 1134: in the outer edge of blade 11h, substantiallyas is shown. This is illustrated in FIG. ilil. FIG. ilil alsoillustrates the fact that when the cam releases both blades M and 18,only the blade 116 will return toward its rest position to effect theshutter speed action, since the blade id remains stationary and hencethe shutter speed action will be one half the speed of the effectachieved in conjunction with the operation described with respect toFIGS. 1-7 Thus, the blade 316 will sweep its opening dd into registry oralignment with the opening dd in the blade ilh which, in its cockedposition, is aligned with the opening 46, th of the casing assembly, aspreviously described. Thus, the opening at in the blade 18 takes no partin the shuttering action as was the case for the high speed shuttereffect previously described.

As the blade 114$ moves toward and into its rest position, it strikesthe head 11% of the latch mechanism and cams it outwardly so that thehead disengages from within the notch 1134 in the blade 18, thusallowing same to be moved from its cocked to its normal position, duringwhich movement no shutter action takes place because of the dispositionof the aperture or window M in position past the apertures 416, Mt.

As has been mentioned, the lost motion connection of the secondary camarm assembly dd with respect to the primary cam arm assembly 3% and theshaft 34 prevents undesirable feedback of torque to the shaft 3%, andthe driving mechanism therefor, when the cam followers 83 and [t5 dropoff the ends of the arms of the assembly, by allowing the secondary camarm assembly to kick back" due to its lost motion. in addition to thisprotecting feature, the lost motion and consequent kick back" perform afurther and very important function. This further function is that theaction described positively assures that the two blades aresimultaneously released and, further, that the timing of this release isvery precise. With respect to simultaneous release, it will beappreciated that if there is any tendency for either cam follower 83 or85 to drop off before the other, the kicking back of the secondary camarm assembly 40 due to this drop off will assure immediate andsubstantially simultaneous release or drop off of the other camfollower. As to the precision 10 of timing, it will be seen that thekick back feature creates a condition in which the releasing or drop offaction is very abrupt and has practically no transition time betweenfully-held and drop off conditions. The essentially line-contactrelation between the followers 83 and 85 and the cam arms materiallyaids in this lack of transition.

What is claimed is:

1. A between-the-lens shutter assembly for photographic equipment,comprising in combination;

a casing defining a cavity having a geometric center and havingoppositely facing outer surfaces, said surfaces being provided withopenings radially offset from said geometric center and defining anaperture therethrough;

lens elements engaging said surfaces and closing said openings;

optical coupling liquid filling said cavity to couple said lenselements;

shutter means housed within said casing for selectively permitting lightto pass through said aperture, said shutter means including a pair ofshutter blades pivotally mounted about an axis near said geometriccenter and projecting radially therefrom to sweep back and forth overthe region between said apertures and in parallel planes perpendicularto the axis of said aperture, said shutter blades having openings whichregister with said aperture in intermediate positions of said blades;

means for biasing said blades to normal positioning;

and

cam means for sequentially cocking and then releasing said shutterblades.

2. The between-the-lens shutter assembly as defined in claim 1 includingmeans for selectively altering the shutter speed effect of said shuttermeans.

3. A between-the-lens shutter assembly for photographic equipment,comprising in combination:

a casing defining a cavity and having oppositely facing outer surfaces,said surfaces being provided with openings defining an aperturetherethrough;

lens elements engaging said surfaces and closing said openings;

optical coupling liquid filling said cavity to couple said lenselements;

shutter means housed within said casing for selectively permitting lightto pass through said aperture, said shutter means including a pair ofshutter blades pivotally mounted to sweep back and forth over the regionbetween said apertures and in parallel planes perpendicular to the axisof said aperture, said shutter blades having openings which registerwith said aperture in intermediate positions of said blades;

means for biasing said blades to normal positioning;

and

cam means for sequentially cocking and then releasing said shutterblades, said blades being pivotally mounted about a common axis and saidmeans for biasing urging said blades in relatively opposite directions,and means for selectively latching one of said blades in cocked positionto create a slow shutter speed effect.

4. The between-the-lens shutter assembly as defined in claim 3 whereinthe other of said blades unlatches said one blade when said other bladereturns to its normal position.

5. A shutter assembly for photographic equipment comprising, incombination;

means for defining an aperture through which light is to be admittedunder control of a shutter assembly to pass through an associatedoptical system;

a pair of overlapped shutter blades normally blocking said aperture;means for pivotally mounting said shutter blades for movement betweencocked and normal positions about an axis offset with respect to saidaperture;

means for biasing said shutter blades in relatively opposite directionsabout said axis to reside in their normal positions;

cam means for camming first one of said blades and then the other ofsaid blades to their cocked positions in opposition to said biasingmeans and thereafter to disengage said blades simultaneous whereby theymay be returned by said biasing means to their normal positions; and

each shutter blade having an opening therein positioned so that the twoblades register their openings with each other and with said apertureduring movement of said blades from their cocked to their normalpositions.

6. The shutter assembly as defined in claim 5 wherein said cam meanscomprises a rotary cam having at least a pair of primary radial armsdisposed in angularly spaced relation with respect to the axis ofrotation of said cam, said cam having a pair of secondary radial armsassociated with said primary arms, said primary and said secondary armsbeing offset with respect to each other longitudinally of said axis ofrotation;

means for rotating said cam in one direction about its axis of rotation;and

said one blade having a follower engaged sequentially by said primaryarms and said other blade having a follower engaged sequentially by saidsecondary arms.

7. The shutter assembly as defined in claim 5 including at least theopening in said other blade which is cocked last being out of registrywith said aperture when said other blade is in its normal position andat least the opening in said one blade which is cocked first being outof registry with said aperture when said one blade is in its cockedposition, whereby at least one blade is always blocking said apertureduring the sequential cocking of said blades.

8. The shutter assembly as defined in claim 7 wherein that blade whichis cocked last also includes an opening registering with said aperturewhen such blade is cocked, and means for selectively latching the lastcocked blade in cocked position to effect a slow shutter speed effectwhen said blades are released by said cam means.

9. The shutter assembly as defined in claim 8 wherein the last meansincludes a latch element and means for shifting said blades relative tosaid latch element.

10. A shutter assembly as defined in claim 6 wherein said secondaryradial arms are connected in lost-motion relation to said primary armswhereby precise and substantially simultaneous release of said shutterblades is assured.

11. A shutter assembly for photographic equipment comprising, incombination:

means for defining an aperture through which light is to be admittedunder control of a shutter assembly to pass through an associatedoptical system;

a pair of overlapped shutter blades normally blocking said aperture;

means for mounting said shutter blades for movement between cocked andnormal positions with respect to said aperture;

means for biasing said shutter blades to reside in their normalpositions; and

cam means for camming said shutter blades from their normal to theircocked positions and then to release them, said cam means includinglost-motion means for assuring precise and substantially simultaneousrelease of both shutter blades.

12. A shutter assembly as defined in claim 11 wherein said cam meanscomprises a multi-arm primary cam and a drive shaft to which saidprimary cam is affixed, said lost-motion means comprising a multi-armsecondary cam connected to said drive shaft for limited lost-motion withrespect thereto.

13. A shutter assembly as defined in claim 12 including a cylindricalcam follower carried by each of said shutter blades engageable by thearms of said primary and secondary cams and making essentially linecontact therewith to assure precise and simultaneous release of bothshutter blades.

14. A shutter assembly as defined in claim 12 including a casing housingsame and a quantity of optical coupling liquid filling said casingoptically to couple a pair of separated lens elements between which saidcasing is positioned.

1. A between-the-lens shutter assembly for photographic equipment,comprising in combination; a casing defining a cavity having a geometriccenter and having oppositely facing outer surfaces, said surfaces beingprovided with openings radially offset from said geometric center anddefining an aperture therethrough; lens elements engaging said surfacesand closing said openings; optical coupling liquid filling said cavityto couple said lens elements; shutter means housed within said casingfor selectively permitting light to pass through said aperture, saidshutter means including a pair of shutter blades pivotally mounted aboutan axis near said geometric center and projecting radially therefrom tosweep back and forth over the region between said apertures and inparallel planes perpendicular to the axis of said aperture, said shutterblades having openings which register with said aperture in intermediatepositions of said blades; means for biasing said blades to normalpositioning; and cam means for sequentially cocking and then releasingsaid shutter blades.
 2. The between-the-lens shutter assembly as definedin claim 1 including means for selectively altering the shutter speedeffect of said shutter means.
 3. A between-the-lens shutter assembly forphotographic equipment, comprising in combination: a casing defining acavity and having oppositely facing outer surfaces, said surfaces beingprovided with openings defining an aperture therethrough; lens elementsengaging said surfaces and closing said openings; optical couplingliquid filling said cavity to couple said lens elements; shutter meanshoused within said casing for selectively permitting light to passthrough said aperture, said shutter means including a pair of shutterblades pivotally mounted to sweep back and forth over the region betweensaid apertures and in parallel planes perpendicular to the axis of saidaperture, said shutter blades having openings which register with saidaperture in intermediate positions of said blades; means for biasingsaid blades to normal positioning; and cam means for sequentiallycocking and then releasing said shutter blades, said blades beingpivotally mounted about a common axis and said means for biasing urgingsaid blades in relatively opposite directions, and means for selectivelylatching one of said blades in cocked position to create a slow shutterspeed effect.
 4. The between-the-lens shutter assembly as defined inclaim 3 wherein the other of said blades unlatches said one blade whensaid other blade returns to its normal position.
 5. A shutter assemblyfor photographic equipment comprising, in combination; means fordefining an aperture through which light is to be admitted under controlof a shutter assembly to pass through an associated optical system; apair of overlapped shutter blades normally blocking said aperture; meansfor pivotally mounting said shutter blades for movement between cockedand normal positions about an axis offset with respect to said aperture;means for biasing said shutter blades in relatively opposite directionsabout said axis to reside in their normal positions; cam means forcamming first one of said blades and then the other of said blades totheir cocked positions in opposition to said biasing means andthereafter to disengage said blades simultaneous whereby they may bereturned by said biasing means to their normal positions; and eachshutter blade having an opening therein positioned so that the twoblades register their openings with each other and with said apertureduring movement of said blades from their cocked to their normalpositions.
 6. The shutter assembly as defined in claim 5 wherein saidcam means comprises a rotary cam having at least a pair of primaryradial arms disposed in angularly spaced relation with respect to theaxis of rotation of said cam, said cam having a pair of secondary radialarms associated with said primary arms, said primary and said secondaryarms being offset with respect to each other longitudinally of said axisof rotation; means for rotating said cam in one direction about its axisof rotation; and said one blade having a follower engaged sequentiallyby said primary arms and said other blade having a follower engagedsequentially by said secondary arms.
 7. The shutter assembly as definedin claim 5 including at least the opening in said other blade which iscocked last being out of registry with said aperture when said otherblade is in its normal position and at least the opening in said oneblade which is cocked first being out of registry with said aperturewhen said one blade is in its cocked position, whereby at least oneblade is always blocking said aperture during the sequential cocking ofsaid blades.
 8. The shutter assembly as defined in claim 7 wherein thatblade which is cocked last also includes an opening registering withsaid aperture when such blade is cocked, and means for selectivelylatching the last cocked blade in cocked position to effect a slowshutter speed effect when said blades are released by said cam means. 9.The shutter assembly as defined in claim 8 wherein the last meansincludes a latch element and means for shifting said blades relative tosaid latch element.
 10. A shutter assembly as defined in claim 6 whereinsaid secondary radial arms are connected in lost-motion relation to saidprimary arms whereby precise and substantially simultaneous release ofsaid shutter blades is assured.
 11. A shutter assembly for photographicequipment comprising, in combination: means for defining an aperturethrough which light is to be admitted under control of a shutterassembly to pass throUgh an associated optical system; a pair ofoverlapped shutter blades normally blocking said aperture; means formounting said shutter blades for movement between cocked and normalpositions with respect to said aperture; means for biasing said shutterblades to reside in their normal positions; and cam means for cammingsaid shutter blades from their normal to their cocked positions and thento release them, said cam means including lost-motion means for assuringprecise and substantially simultaneous release of both shutter blades.12. A shutter assembly as defined in claim 11 wherein said cam meanscomprises a multi-arm primary cam and a drive shaft to which saidprimary cam is affixed, said lost-motion means comprising a multi-armsecondary cam connected to said drive shaft for limited lost-motion withrespect thereto.
 13. A shutter assembly as defined in claim 12 includinga cylindrical cam follower carried by each of said shutter bladesengageable by the arms of said primary and secondary cams and makingessentially line contact therewith to assure precise and simultaneousrelease of both shutter blades.
 14. A shutter assembly as defined inclaim 12 including a casing housing same and a quantity of opticalcoupling liquid filling said casing optically to couple a pair ofseparated lens elements between which said casing is positioned.